Objectives: (1) To find the earliest enzymatic reaction in polyterpene metabolism that is photoactivated in Mycobacteria. (2) Isolate and purify the prenyl transferase from Mycobacteria that catalyzes the synthesis of the higher polyprenols. Of special interest is substrate specificity and the generation of poly cis prenols. (3) Purification of diprenyl transferase from yeast with specific reference to substrate specificity. (4) Evaluation of branch and control points in terpene metabolism of PHycomyces. This organism probably has multiple control points early in the biosynthetic sequence.